For example, PTL 1 is known as a technology for managing a computer system. In PTL 1, the following processing is performed. That is, in response to detection of changes of resources in a computer to be managed, an agent resident on the computer to be managed notifies a manager on an operation management server of contents of the change of resources. In a change plan DB (database) on the operation management server, contents of resource changes to be planed for individual resource changes for computers to be managed are registered. The manager checks whether the contents of the resource change notified from the agent follow a plan of the resource change registered in the change plan DB. If the contents of the resource change follow the plan, the manager registers the fact that the resource change registered in the change plan DB has completed as planned.